In general, air purification filters have been used for the purpose of removing dust, germs and other contaminants in a room air.
Such air purification filters have a porous structure, and contaminants can be adsorbed and removed, but the adsorbed contaminants are piled up over time, and the air purifying function is deteriorated and the filter has to be replaced continuously, which is however uneconomical.
Therefore, the life of the filter may be extended by decomposing and removing the adsorbed contaminants by activating water, oxygen, etc. contained in the air by using a photocatalyst.
However, in order to coat the filter with such photocatalyst, a binder material was required to use, which may clog the pores of the filter or attach to the surface of the photocatalyst, thereby lowering the surface activity of the photocatalyst to light.
In addition, even when an alcohol solvent is used to rapidly coat the photocatalyst, the surface activity of the photocatalyst may be lowered.